Antihunting system for electrical regulators



Oct 17, 0 H. s. HAAS ANTIWNTING SYSTEM FOR ELECTRICALREGULATORSINVENTOR. HAROLD G. HAAS Filed Aug. .23. 1949 y ATTORNEY Patented Oct.17, 1950 ANTIHUNTING SYSTEM FOR ELECTRICAL REGULATORS Harold G. Haas,Belleville, N. J., assignor to Bendix Aviation Corporation, Teterboro,N. 1., a corporation of Delaware Application August 23, 1949, Serial No.111,888

4 Claims.

The subject application relates to an antihunting circuit for anelectrical regulator and more particularly to improvements in a controlcircuit of the type disclosed in the copending applications Serial No.21,886, filed April 19, 1948 by Harold G. Haas, now U. S. Patent No.2,499,272 and Serial No. 57 254, filed October 29 1948 bv Lawrence E.Gartner and Joseph W. Allen, both of which applications have beenassigned to the same assignee as the present application.

In the present application, there is provided a regulator system such asshown in the application Serial No. 57,254 with the addition of anauxiliary regulator coil which aids and lags the main regulator coilampere turns so as to provide a follow-up action increasing thestability of the system. The lagging ampere turns of the auxiliary coilis caused by variance with current flow in the resistance of suitablelamp filaments connected in series with the auxiliary coil and acrossthe field of the exciter so as to tend to wipe out the follow-up actionof the auxiliary coil in a retarded manner.

In distinction over the system disclosed and claimed in the Haas U. S.Patent No. 2,499,272, the anti-hunting action of the follow-up coil ofthe present disclosure is furthered by the action of an anti-huntingtransformer also connected across the field of the exciter andcooperating with the auxiliary coil in effecting the anti-hunting actionin which the transformer responds more quickly to change than theauxiliar coil so that the follow-up effect of the anti-huntingtransformer is wiped out more rapidly while the time constant of theauxiliary coil is greater than that of the anti-hunting transformer andthe follow-up effect of the auxiliary coil is wiped out more slowly dueto the time lag for the heating or cooling of the lamp filaments uponchange in excitation of the exciter field.

An object of the present invention therefore is to provide an improvedanti-hunting system in which an auxiliary regulator coil and achanging-resistance-with-current conducting device connected across anexciter field introduces a relatively slowly acting anti-huntingcomponent which cooperates with a main regulator coil having connectedin the energizing circuit thereof an anti-hunting transformer connectedacross the exciter field to effect an anti-hunting bias in the maincontrol winding which is more rapidly responsive to change in theexciter field energizing current than the auxiliary coil.

The above and other objects and features of the invention will appearmore fully hereinafter ill 2 from a consideration of the followingdescription taken in connection with the accompanying drawing where oneembodiment of the invention is illustrated by way of example. In thedrawing, there is illustrated diagrammatically an embodiment of ourinvention.

Referring now to the drawing, there is shown an alternating currentgenerator or alternator l which is connected to supply power to anexternal load circuit through conductors 2. Alternator I is providedwith a field winding 3 which is energized by exciter 4 having a shuntfield winding 5. Connected in series with the field winding 5 of theexciter 4 by a conductor 6 is a variable resistance carbon pileelement 1. The resistance element 1 is connected at its opposite end bya conductor 9 to an output terminal of the exciter 4. The oppositeoutput terminal of the exciter 4 is connected by a conductor H to theexciter field winding 5.

Thus, the excitation of the exciter field winding 5 is controlled by thevariable resistance carbon pile element 1. The variable resistancecarbon pile element 1 may be embodied in a regulator 12 of a type suchas shown in U. S. Patent No. 2,427,805, granted September 23, 1947 to W.G. Neild and assigned to Bendix Aviation Corporation.

The regulator l2 may include a main control winding l3 arranged tocontrol an armature !5 shown diagrammatically herein as pivoted at I!and exerting a compressive force upon the carbon pile 1 under tension ofa spring IS. The spring I! is arranged so as to balance the pull on thearmature by the electromagnetic winding l3 when energized by a linevoltage having a predetermined value, as described in greater detail inthe aforenoted patent.

Interposed between alternator output 2 and the main control coil I3 is afull wave rectifier 2| which may be of any suitable type such as thewell known copper oxide variety.

'Ihereis further provided a transformer comprising a core 23 having aprimary winding 25 connected so as to have its energization varied inaccordance with the operation of the regulator 1 and, as shown, it isconnected across the terminals of the field winding 5 of the exciter 4through conductors 21 and 29.

Also wound on the core '23 is a secondary winding 3| inductively coupledto the primary winding 25 and connected so as to apply a transientcorrective or anti-hunting bias to the control coil I3. The primarywinding 25 induces such bias into the secondary winding 3| during changein the voltage across the field winding 5. As shown, the secondarywinding 3| is connected in series with the main control coil l3 on theoutput or direct current side of the rectifier 2|, as disclosed andclaimed in U. 8. Patent No. 2,211,612, granted August 13, 1940 to L. W.Thompson and assigned to General Electric Com- D 3- There is furtherprovided an exciter control indicated generally by the numeral 35 anddisclosed and claimed in the copending application Serial No. 57,254,filed October 29, 1948 by Lawrence E. Gartner and Joseph W. Allen andassigned to the assignee of the present application.

The exciter control 35 includes resistor elements 31 and 33 connected atone end by a conductor 4| to an output terminal of the exciter 4, whilethe opposite end of the resistance elements 31 and 33 are connected by aconductor 43 to one end of a main control electromagnetic winding 45wound on a magnetic core 45. The opposite end of the winding 45 isconnected by a conductor 41 to the alternator field winding 3 which isin turn connected at the opposite end through conductor 43 to the otheroutput terminal of the exciter 4.

It will be seen then that when the resistor elements 31 and 39 areinserted between output conductor 4| of the exciter 4 and the fieldwinding 3 o! the alternator energization oi. the alternator field 3 ismaterially reduced.

A main control switch having an armature 52 cooperating with the core 45is arranged to shunt the resistance elements 31 and 39 out of operationupon closing contacts 53 and 54 connected to conductors 4| and 43respectively. The latter main control switch 5| is normally biased to anopen position by a spring 55 and is biased to a closed position by thecombined electromagnetic forces of the main control winding 45 and anauxiliary winding 55 acting on armature 52.

The ampere turns of the windings 45 and 56 act in additive relation.Energization of the auxiliary winding 55 is controlled by a pilot relaywinding 51 connected by conductors 58 and 59 across the resistorelements 31 and 39.

Connected in the conductor 59 is a swamping resistor 6| which may be soadjusted that the closing of the main switch 5| controlled by the pilotrelay winding 51 is set to the desired closing current and hence voltagevalue. The pilot relay 51 operates relay switch elements 53 and 55 tocontrol energization of the auxiliary winding 56 by shunting auxiliarywinding 56, at the predetermined voltage, across resistors 31 and 33through conductors 43 and 58, switch arms 53 and 55, conductor 51,auxiliary winding 55 and conductors 1|, 53 and 4|.

Thus, upon the closing of switch elements 53 and 35, the auxiliarywinding 58 is energized by the drop across the main resistors 31 and 39so as to cause with the main control winding 45 the closing of the maincontactor 5|. On the closing of the main control switch 5|, the mainresistors 31 and 39 are shorted out, reducing the voltage drop acrossthe resistors 31 and 33 to substantially zero.

With the zero voltage, the pilot relay 51 permits switch arms 53 and 55to be biased under inherent spring tension in a direction to open thecircuit of the auxiliary winding 56 of the main contactor. The maincontactor 5|, however, remains closed by virtue of the ampere turns ofthe series winding 45 which is sufilcient to maintain the main contactor5| closed due to the shunting .j i H ,I: a g of resistors 31 and '33and'the in air gap between the core and armature 52. However, as thecurrent in the alternator field 3 drops, the main contactor 5|controlled by the winding 45 will open at a current value governed bythe ampere turns of the series winding 45 and adjustment or the biasingspring 55.

' Upon the opening of contactor 5| resistors 31 and 33 are againinserted in the field winding 3 of the alternator I.

As such, the difierential between closing and drop out of the maincontactor 5| is a controllable iunction of the current in the fieldwinding 3 of the alternator. When installed in a complete system,operation is as follows: at the minimum speed of the alternator the maincontactor 5| remains closed for all load conditions. At higher operatingspeeds and under lightly loaded conditions, the main contactor 5| opens,and inserts the main resistance in the alternating field 3. For fullyloaded conditions the contactor 5| necessarily remains closed at allspeeds.

Thus, upon the current to the field winding 3 exceeding a predeterminedminimum value set by the adjustment of the swamping resistor 5|, theresistors 31 and 33 are shunted out of the circuit of the field winding3 by the closing of main switch 5| and regulation or the alternatoroutput is efiected through carbon pile regulator i2. However, when thecurrent to the field winding 3 falls below a predetermined minimum theseries winding 45 permits switch 5| to open under tension of the spring55 inserting the resistors 3; and 33 into the circuit of the fieldwinding 3 so that regulation of the output of the alternator maycontinue to be effected by the regulator l2 without tending to buzz ortirrill.

Anti-hunting circuit The novel feature of the present application is theprovision of an auxiliary winding or coil 13 connected at one end by aconductor 12 to conductor 31 and at the opposite end by a conductor 14to the conductor 23. Thus the auxiliary winding or coil 13 is connectedacross the exciter field winding 5 through conductors 21, 12, 14 and 23and is eiiected by the voltage applied to the exciter winding 5. Theauxiliary coil 13 acts on the armature l5 of the regulator I! inadditive relation to the main coil 3 so that upon change in the voltageapplied to the exciter field 5 due to adjustment of the carbon pile 1,the auxiliary coil 13 acts so as to temporarily inhibit further change.

Connected in the conductor 14 are filaments 11 of lamps 13 which form apart of the energizing circuit for the anti-hunting or follow-up winding13. The filaments 11 are such that as the temperature of the filaments11 rises with increase in current fiow the resistance of the filaments11 to current fiow likewise increases with a lag in time so as tocounteract the inhibiting eflect and decreases the energization of thewinding 13 to cause a corresponding resetting of the winding 13.

Upon a change in an opposite sense, a decrease in the current fiowthrough the filaments 11 will cause a decrease in the temperature and inthe resistance of the filaments 11 upon a similar time lag and aresetting of the winding 13 with a corresponding increase in theenergization of t e winding 13.

Thus the heating lag of the filaments 11 introduces a rate componentinto the energizing circuit for the anti-hunting winding 10.

This rate component is such that the effect of the winding on theregulator I2 is wiped out more slowly than the anti-hunting biasintroduced into the main control winding l3 of the regulator I! by theanti-hunting transformer 2! upon change in the voltage across theexciter field winding 5. The anti-hunting component thus introduced bythe anti-hunting winding 10 and lamp filaments l1 cooperate with theantihunting bias introduced in the main control winding is by theanti-hunting transformer 23 upon change in the voltage across theexciter field 5. Due to the time constant of the lamp filaments 11 thefollow-up bias applied by the winding 10 is eliminated more slowly thanthe transitory follow-up bias applied by transformer 23 to the maincontrol winding is. This slower action may be attributed to the time lagfor theheating or cooling of the lamp filaments 11 upon change inexcitation of the exciter field winding 5.

Further the time constant of the auxiliary winding 10 is greater thanthat of the antihunting transformer 23 so that the transformer 23responds more quickly to change than the auxiliary winding 10, while thefollow-up effect of the auxiliary winding 10 is wiped out more slowly soas to efiectgreater stability of control in the system described.

Although only one embodiment of the invention has been illustrated anddescribed, various changes in the form and relative arrangements of theparts may be made to suit requirements.

What is claimed is:

l. A regulating system comprising, in combination, a source ofelectrical energy, means for controlling a function of the output ofsaid source, means for regulating a condition of said control means inresponse to the output of said source, said regulating means'including afirst means responsive to change of condition of said control means andefi'ective only during such change of condition of said control means totemporarily inhibit further change by said regulating means, secondmeans responsive to change of condition of said control means totemporarily inhibit further change by said regulating means, and a resetmeans connected in series relation with said second inhibiting means forcounteracting said last mentioned inhibiting efiect in a retardedmanner. a

2. A regulating system comprising, in combination, a generator supplyingline current to a variable load and including an exciter field winding,means for controlling the excitation of said exciter field winding, amain control winding to regulate said control means in response to theoutput of said generator, a transformer including a primary windingconnected across the exciter field winding and a secondary windinginducperature for counteracting said inhibiting effect tively coupled tothe primary winding and connected in series with said main controlwinding so as to apply thereto a bias induced in the secondary windingby the primary winding during change in the excitation of said fieldwinding and tending to temporarily inhibit further change by saidcontrol means, an auxiliary winding cooperating with said main windingand connected across the exciter field winding and cooperating with saidtransformer upon such change in the excitation of said field winding totemporarily inhibit further change by said control means, and a changingresistance with current conducting device connected in series with saidauxiliary winding across the exciter field, said device arranged toincrease the resistance of said series connection with current fiow in aretarded manner so as to substantially eliminate the last mentionedinhibiting effect of said auxiliary winding.

3. A regulator for a generator supplying line current to a variable loadand including an exciter field, comprising a variable resistor, anarmature operatively connected thereto, a spring biasing a portion ofthe armature to tend to operate said resistor in the direction toproduce an increase in the exciter field current, a first windingtending to operate the armature in the opposite direction upon anincrease of the regulated quantity, a transformer including a primarywinding responsive to change in the exciter field current and asecondary winding inductively coupled to the primary winding andconnected in series with the first winding so as to apply to the firstwinding a transitory bias during change in the exciter field currenttending to temporarily inhibit further change in the resistance of saidresistor. a second winding having a greater time constant than saidtransformer and more slowly responsive to change of said quantity tobias the-armature as an additional follow-up limiting the change ofresistance of said resistor, a reset means connected in series with saidsecond winding across the exciter field, said reset means including asecond variable resistor element arranged so as to increase theresistance of said series connection in response to increase intemperature of said element with current fiow in a retarded manner so asto substantially eliminate the stated follow-up bias of the secondwinding, and the time lag for change in the temperature of said elementbeing such that the follow-up bias of said second winding is eliminatedmore slowly than the transitory follow-up bias applied to said firstwinding through said transformer.

4. The combination defined by claim 1 in which said reset means includesa lamp filament having a variable resistance which increases with temina retarded manner.

- HAROLD No references cited.

